Water Pressure And Slurry Flow Field Control Method Of Slurry Shield Tunneling In High Water Pressure Pebbie Layer

Based on the research background of the mud-water shield section of the Xiaolangdi Yelow River Diversion Project in Shanxi.This paper studies the construction problem of muddy water shield in high water pressure pebble layer section,studies the mechanism and method of controlling high water pressure with precipitation and controlling pebble layer with flow field by means of theoretical analysis,field test,numerical simulation and mechanism analysis,etc.And the mechanism and method of using the flow field to control the pebble layer,and implemented in the shield tunnel excavation parameter control,used to solve the Xiaolangdi Project and similar highpressure mud-water shield construction problems.Main research content and results list:(1)Site pumping test of mud-water shield with high water pressure pebble layerIn order to find out the permeability characteristics of the high-pressure pebble layer,a field pumping test was carried out.The construction site dewatering wels were used as pumping wels and observation wels,remotely controlled wireless water level gauges and flow meters were deployed,and single well and group well tests were used to analyze groundwater.The law of drawdown and hydrogeological parameters(permeability coefficient 22m/d),provide basis for high water pressure precipitation decompression control.(2)Numerical simulation of precipitation of mud water shield with high water pressure pebble layerThe numerical model of the field test was established,use the pumping test data to carry out the back analysis work,correct the model data.Then,numerical simulation of falling water under different working conditions is carried out for high water pressure control of muddy high water shield tunnel,and demonstrate that the double side wells alternate dewatering control high water the feasibility of pressure.(3)Mud-pebble coupling mechanism of mud-water shield with high water pressure pebble layer.Using the coupling method of CFD and discrete element to establish a mathematical model,the fluid dynamics of the mud flow field under the rotating condition of the cutter head of the slurry shield machine is studied;the law of pebble accumulation under different tunneling parameters is studied.Through simulation research,it is concluded that the internal flow of the shield is basically unobstructed,but the flow velocity in the rotation area of the cutter head(central zone)is relatively low,which is 2-3 orders of magnitude different from the flow velocity in the edge area of the cutter head.The central area of the cutter head is prone to sludge problems.After the sludge particles are stripped,a large amount of them are deposited under the cutter head,and the muddy water has a weak ability to carry the sludge.(4)Monitoring analysis and control model of on-site construction control mechanism of slurry shield with high water pressure pebble layerUsing shield tunnel construction monitoring analysis,the relationship between shield tunneling parameters in different strata is studied,and the influence of different strata on shield tunneling parameters is analyzed.It is concluded that in the high water pressure pebble zone,the shield it is recommended to use small thrust(3000k N),large torque,and medium cutter head rotation(1.6rpm)for the tunneling parameters of the construction machine,which is conducive to the punching of the pebbles by the cutter head.Study the correlation between tunneling parameters,and establish a predictive control model of related parameters on engineering geology(stratum).